Download - Finite Element Analysis of Castellated Steel - MR WAKCHAURE, A v SAGADE

8/13/2019 Finite Element Analysis of Castellated Steel - MR WAKCHAURE, A v SAGADE

http://slidepdf.com/reader/full/finite-element-analysis-of-castellated-steel-mr-wakchaure-a-v-sagade 1/8

ISSN: 2277-3754International Journal of Engineering and Innovative Technology (IJEIT)

ISO 9001:2008 Certified

Volume 2, Issue 1, July 2012

365

Abstract — Use of castellated beam for various structures

rapidl y gaining appeal. Th is is due to incr eased depth of section

without any additional weight, high strength to weight ratio,

their lower maintenance and painting cost. The principle

advantage of castell ated beam is increase in vert ical bending

stif fness, ease of service provision and attr active appearance.

However one consequence of presence of web openi ng i s the

development of various local eff ects. I n thi s paper steel I section

was selected, castell ated beams were fabr icated with i ncrease in

depth of web openi ngs. To analyze the behavior of castell ated

steel beams having an I -shaped cross-section, modeli ng is

conducted using finite element software package ANSYS14.

Anal ysis is carri ed out on beam with two point load and simply

supported support conditi on. The defl ection at centre of beam

and study of vari ous fail ure patterns are studied. The beams with

increase in depth are then compared with each other and with

parent section f or vari ous parameters and for servi ceabili ty

cri teria. F rom the fi ni te element analysis resul ts, it i s concluded

that, the Castellated steel beam behaves satisfactorily with

regards to serviceabili ty requir ements up to a max imum web

opening depth of 0.6h. Castell ated beams have proved to be

effi cient for moderately loaded longer spans where the design iscontrol led by defl ection .

I ndex Terms - Castellated Beam, Web Opening, Cellular

Beam, Virendeel Mechanism, Plastic Hinges.

I. INTRODUCTION

Engineers are constantly trying to improve the materials

and practices of design and construction. One such

improvement occurred in built-up structural members in the

mid-1930, an engineer working in Argentina, Geoffrey

Murray Boyd, is castellated beam. Castellated beams are

such structural members, which are made by flame cutting arolled beam along its centerline and then rejoining the two

halves by welding so that the overall beam depth is increased

by 50% for improved structural performance against

bending. Since Second World War many attempts have been

made by structural engineers to find new ways to decrease the

cost of steel structures. Due to limitations on minimum

allowable deflection, the high strength properties of

structural steel cannot always be utilized to best advantage.

As a result several new methods aimed at increasing stiffness

of steel member, without any increase in weight of steel

required. Castellated beam is one of the best solutions.

The responsibility of a Structural Engineer lies in not

merely designing the structure based on safety and

serviceability considerations but he also has to consider the

functional requirements based on the use to which the

structure is intended. While designing a power plant

structure or a multi-storied building, the traditional

structural steel framing consists of beams and girders with

solid webs. These hinder the provision of pipelines and air

conditioning ducts, electrical wiring required for satisfactory

functioning for which the structure is put up.

The re-routing of services (or increasing the floor height at

the design stage for accommodating them) leads to additional

cost and is generally unacceptable. The provision of beams

with web openings has become an acceptable engineering

practice, and eliminates the probability of a service engineer

cutting holes subsequently in inappropriate locations. Beams

with web openings can be competitive in such cases, even

though other alternatives to solid web beams such as stub

girders, trusses etc are available. This form of construction

maintains a smaller construction depth with placement of

services within the girder depth, at the most appropriate

locations. The introduction of an opening in the web of the

beam alters the stress distribution within the member and

also influences its collapse behavior.

Fig.1 Terminology

Web Post: The cross-section of the castellated beam where

the section is assumed to be a solid cross-section.

Throat Width: The length of the horizontal cut on the root

beam. The length of the portion of the web that is included

with the flanges.

Throat Depth: The height of the portion of the web that

connects to the flanges to form the tee section.

II. FORMULATION OF RESEARCH OBJECTIVESTo achieve economy, castellated beam fabricated from its

parent solid webbed „I‟ section should have maximum

possible depth. An available literature does not deal with the

Finite Element Analysis of Castellated Steel

BeamM.R.Wakchaure, A.V. Sagade






368

Fig.6 Position Of force application for Ic 210

Fig.7 Total Deflection of ISMB 150

Fig.8 Total Deflection of Ic 210 mm

Fig.9 Total Deflection of Ic 225 mm

Fig. 10 Total deflection for Ic 240

Fig.11 Maximum Stress of ISMB 150mm






369

Fig.12 Maximum Stress of Ic 210mm



IV. R ESULTS OF ANSYS ANALYSIS

All Tables are shown in Appendix.

Graph.1Load v/s Deflection ISMB150

Graph.2 Load v/s Deflection for Ic210







370


Graph.5 Comparision of Ansys Results

The beams tested above cannot be compared directly

among themselves because of different failure modes of

beams.

Serviceability limit for beam= L/325

=1900/325

= 5.846 mm

V. CONCLUSION

From the finite element analysis results, it is concluded

that, the Castellated steel beam behaves satisfactorily with

regards to serviceability requirements up to a maximum web

opening depth of 0.6h. Castellated beams have holes in its

web, which lead to local effects in the beams. This causes the beams to fail in different local failure modes, which reduces

their virgin load carrying capacity. Hence, it is irrational to

compare the structural behavior of beams having different

modes of failure, based only on strength criteria.

The finite element analysis effectively captured the

different failure modes of all the beams. From this analysis, it

was observed that as the depth of opening increases, stressconcentrations increases at the hole corners (Vierendeel

effect) and at load application point. The results also confirm

that the flexural stiffness of castellated beams decrease as the

depth of opening increases. So by taking corrective measures,

i.e. by rounding hole corners, providing reinforcement at

critical section, providing plate below point load, etc. the

serviceability performance of castellated beams can be

improved in practice. It is conclude that the castellated beams

are well accepted for industrial buildings, power plant and

multistoried structures, where generally loads are less and

spans are more with its economy and satisfactory

serviceability performance.

REFERENCES[1] Richard Redwoodland Sevak Demirdjian “Castellated Beam

Web Buckling In Shear” Journal of Structural Engineering

1october 1998/1207.

[2] Tadeh Zirakian, Hossein Showkati “Distortional Buckling of

Castellated Beams” (Journal of Constructional Steel R esearch

62, pp. 863 – 871, 2006

[3] Nikos D. Lagaros, Lemonis D. Psarras, Manolis Papadrakakis,

Giannis Panagiotou “Optimum Design of Steel Structures with

Web Openings” Engineering Structures 30, pp. 2528 – 2537,

2008.

[4] H. R. Kazemi Nia Korrani1, M. Z. Kabir, S. Molanaei “

Lateral-Torsional Buckling of Castellated Beams Under End

Moments” International J. of R ecent Trends in Engineering

and Technology, Vol. 3, No. 5, May 2010.

[5] M.R. Soltani, A. Bouchaïr , “Nonlinear FE analysis of the

ultimate behavior of steel castellated beams”Journal of

Constructional Steel Research 70 (2012), pp. 101 – 114

[6] Ehab Ellobody “Nonlinear Analysis of Cellulars Steel Beams

Under Combined Buckling Modes” (Thin-Walled Structures

52 (2012), pp. 66 – 79).

[7] K.F. Chung a, T.C.H. Liu b, “Journal of Constructional Steel

Research 57 (2001), pp. 467 – 490”.

AUTHOR BIOGRAPHY

Wakchaure M.R. *, ME Structures, Faculty, Civil

Engineering Department, Amrutvahini College of

Engineering, Sangamner, Maharashtra, India.

Sagade A.V. *, ME Structures, Faculty, Civil

Engineering Department, Amrutvahini College of

Engineering, Sangamner, Maharashtra, India.EMAIL: [email protected]






371

Appendix

Table I. Load and Deflections of ISMB 150

&Table II.Load and Deflections of Ic=210

Table.III Load Vs Deflection for Ic 225

&

Table.IV Load v/s Deflection for Ic 240

Sr. No. Load ( kN) Deflection (mm)

1 0 0

2 10 0.43572

3 20 0.87945

4 30 1.3412

5 40 1.7549

6 50 2.1888

7 60 2.5782

8 70 3.0065

9 80 3.4618

10 90 3.8235

11 100 4.2372

12 110 4.651

13 120 5.0647


1 0 0

2 10 0.6648

320 1.3338

430 2.0085

540 2.6839

650 3.3652

760 4.0506

870 4.7402

980 5.4341

10 90 6.1325

11100 6.8345

12110 7.5412

13120 8.2522

Sr.No. Load ( kN) Deflection (mm)

1 0 0

2 10 0.8099

3 20 1.6199

4 30 2.4298

5 40 3.23976 50 4.0497

7 60 4.8596

8 70 5.6695

9 80 6.4795

10 90 7.2894

11 100 8.0993

12 110 8.8534

13 115 9.3143


1 0 0

2 10 0.8934

3 20 1.8018

4 30 2.7130

5 40 3.6347

6 50 4.5686

7 60 5.5123

8 65 5.9880






372

Table V. Comparison of ANSYS Results for Serviceability Limit

Sr. No. Beam Deflection

(mm)

Load by

ANSYS

(kN)

Local Mode Of Failure Global Mode of failure

1 ISMB

150

5.84

135 Failure of compression flange Lateral Torsional buckling

2 Ic 210 85 Failure of compression flange Flexural buckling of Web

3 Ic 225 70 Failure of compression flange and

Vierendeel effect

Web buckling

4 Ic 240 65 Vierendeel effect and Failure of

compression flange

Flexural buckling of Web